In this paper are described some new spinning-tops, gyrostatic apparatus, and illustrations of gyrostatic action devised by the author in the course of the last nine months. The apparatus has been built in the workshops of the Natural Philosophy Institute of the University of Glasgow, and has been employed in illustrating the lectures on rotational motion delivered in the Natural Philosophy classes in the course of the session just closed.

Fig. 1 shows a model aeroplane fitted with a small gyrostat in the position of the propeller. The gyrostat is therefore fixed on the front of the aeroplane with the plane of its flywheel at right angles to the length of the machine. The flywheel of the gyrostat, so fitted, represents exactly the rotor of the engine and the propeller of an actual aeroplane.